New ES250 Trophy Project!

[Blurredman]

Indeed puffs,
Adding the spacers to the float valve is a necessity - I think this may have been the issue, although there is a float overflow, the fuel just comes out of a hole at the front top of the bowl. So I could see something funny was happening at the time.
As for the drain bolt hole, there's a lot of material around the area, it shouldn't be a big deal.. But small problems somehow find a way of becoming a big one..


I've done some more tonight, seeing as the engine coming to life spurred me on somewhat..

I fitted the rear bearing into the sprocket carrier assembly and then fitted that back onto the bike- I do need a new nut for the end of the new hub spindle (because the thread was smashed, my fault), and I fitted the chain at great annoyance. I had to measure it up first with it fitted to the bike as although I bought the standard £10 1/2 x 5/16th chain that was available on mz-b, that i've bought before a few times for my ETZ's, but I had to take out about 5 links.

I started the bike again after trying to eliminate all air leaks that I could find (though I think there are still more so I won't run it too much- It has a bit of an eccentric throttle that is indicitive of air leak- even though the main jet is larger than standard, the main needle is at it's richest and what's more the needle I think has the tip broken anyway).

But, after varying the engine speed a bit and letting it idle, and poking around with the voltage regulator (only after taking the generator off to check for shorts- the resistence is supposed to be 1.7-2.1ohms but is around 3ohms, it isn't shorted at least) the bike suddenly started charging!! - I'm happy with that. So I won't run the engine until I found the air leak. I tried packing the carb entrance with grease etc and putting a little bit more force on those bolts so the engine speed didn't change with carb cleaner, so not sure if maybe it is just the jetting/tuning of the carb now.

I spent the rest of this evening putting the rear brake arms on, and routing the wiring correctly (the neutral light is a PAIN!), and putting footrest on (bent it seems). Also putting on the new bulb connector, although it didn't actually have the metal tang for the earth.. I had to borrow that from the original connector.

I spent a bit of time trying to (unsuccessfully install- it surely doesn't fit) the top headrace bearing dust cover. It's mentioned in the parts diagrammes but for my application it just won't work, maybe there is a slightly different variation- after all mine is a late ES/2 model.

I did have to borrow the plastic clutch spacer thing for the cable (that enters the clutch cover) from another bike, so that's something i'll need to source. What i'll also need to source is a clutch cable- it seems to have a long cable on it (same length as the etz cables I have spare actually), but it's too long- what's more it looks like the speedo cable is also the incorrect one- it's for a TS I think, it's too long for a rear sprocket driven speedo. The speed is measured from the front sprocket on this bike.
The chain covers are also very degraded unfortunately- a big problem i've read with the rubber supplied on the ES bikes. Probably just leave them as they are for now..

Also, i'd like to add, I was wrong that the idle of the engine is adjusted by the carb. A bit.. It IS, but there is always a free-play with the help of a spring in the throttle assembly that doesn't affect the idle. Interesting....

[Puffs]

There is ample description on this one, which seems to have a more modern float bowl:

Bild 123. Schwimmerventil im Schnitt.gif (18.2 KiB) Viewed 18061 times

They mention 30000km for replacement of the fuel valve, but of course for closing off the fuel flow it has to seal properly onto the body too.

That sounds like a well used carb, which is surprising as I thought this bike had only few miles?

Good to hear Alessandro Volta & André-Marie Ampère have joined the party, and good progress!

[Blurredman]

Well I did some more on this last night when I had a bit of time. Just fettling sort of things really....


First off: the jets being different than the manual: This has to be addressed as I have been informed that there were two variations of ES250/2 presumably for certain country classification/laws. One 17.5hp and the other 19hp, the lower HP bikes had the jet sizes I thought I needed, the higher HP bikes have the jet sizes that I actually have. My service manuals are the original 1969 versions that feature the lower hp only, and my haynes also apparently doesn't see the distinction, but there was a revised workshop manual and also haynes manual that has these variations. Basically, the 19hp ES250/2 is the same tune as the ETS.


Secondly, I thought perhaps maybe the issue with idling and slow to return to idle might be air leak. I cannot find one- so I checked the battery, it wasn't being charged. So spend a good while sanding all the contacts on the voltage regulator. Now it charges again. But that didn't necessarily do anything to the throttle. I thought maybe that because the bike wasn't charging, there wasn't load on the engine and therefore it was a 'bit more free'. Anyway..... Brake light works too (seems it doesn't light very positively at idle though). The only bulb which doesn't work now is the front pilot light, but that's okay for now.

Sorry but there are no pictures at the moment. I'm awaiting my bolt in the post and then I think it's time to adjust the chain and then.... test ride it around the estate ..... Exciting!
I think maybe it might be benefitial to the tuning to actually ride it of course.. Once I get a rear plate and insurance, the only real tuning can be done on the road... There's not much point just sitting in the garage and revving it. It needs adjustment whilst in use.

I have a video though to show at least..

video-1631778429.zip

(3.3 MiB) Downloaded 152 times

[Puffs]

Ta for that vid! Nice bike, still some work. It sounds OK, but I might hear some piston slap (no worse than mine and I'm sure it will be addressed at some stage).

I'm a bit surprised to hear the mixture would be different for the different models (with the same carb?), but yes, the jetting you can only do by riding it. And indeed it returns slow to idle. Have you looked at the cylinder base joint? Small gap in overflow port area? There is a trick with WD40 or brake cleaner or so.

[ashthetash]

Loved reading this thread. So glad I joined the forum with the sole purpose of trying to reclaim some garage space.

Congratulations on the rebuild and feel free to take a test ride out to Crickhowell for coffee sometime.

[Blurredman]

The bike is insured on the 9th of Octember, and other than that formality, I just need to make a plate up- then i'll be testing it on the road proper- if all goes to plan for a few weeks, i'll give you a message

[Blurredman]

So, between the time I have spare and fixing other things (damn potholes) and life, I did take this bike to the petrol station a few weeks ago in order to give it a full tank. The bike started to behave a bit better after getting home, but ultimately the ride was poor. Low end was all over the place and the idle was waverying and faulting. And the barrel did seem hotter than I would have expected, considering the ride was 3 miles there and back to the petrol station.

BUT, with brake cleaner I realised (with the advice of Puffs) that the base gasket seemed to be letting air in. I sprayed all over and found the idle of the engine increased when I sprayed around the base gasket (specifically the front left side of the cylinder). I took the barrel off. The old gasket (was in the gasket kit) was split in that area which is annoying I suppose, but I do have gasket paper. It was 0.25mm thick however instead of the 0.37mm. And because I could just about see some unevenness in the flatness of the barrel and crankcase surfaces with a rule, I decided to make two gaskets, and use RTV layer between each componant. I put it all together, and as you can hear (hopefully) a much nicer idle, that doesn't waver or faulter, and a throttle response which is much nicer. It settles back down to idle after smaller and larger throttle input. I've sprayed all around and can detect no change in engine speed. Now notice in the video I am turning on and off the fuel tap within a few seconds, because the float bowl was evacuating petrol. So this is why there is a wet floor.

Now, It ran okayish despite this, but I wondered whether the float valve was blocked or stuck etc. I ran the bike until it died, but despite this upon taking the bowl off it was still full of fuel, which I thought intruiging. With the carb on the bench, the valve seemed good- although letting a bit of my mouth-blowing air through somewhere (I sinched down a bit more on the main valve to seat with those two copper washers I put in for it to sit against instead of the fibre washer that was originally there but broken- that extra tightening sealed it properly).

Anyway, decided to test the float itself, one of them is pierced obviously as it isn't floating properly. As pictured. I would attempt to solder it maybe, but the brass is so corrodded it might take some effort to rub it away and get a good connection with the solder. Moreover, although the float is full of petrol, there is no obvious leak, the hole is so small the petrol isn't leaking from it. Which explains why initially the float worked okay. I do have a brand new spare which I can replace it with - just need to get it from the attic.

Just for reference: Video of it before running: https://mzriders.com/download/file.php?id=6589&sid=586e8f8776aad38abb17531464e801e9
And a video of it running NOW: https://mzriders.com/download/file.php?mode=view&id=6704&sid=586e8f8776aad38abb17531464e801e9


And a picture of the failed float bowl..

[Puffs]

Good you found the leak & that's a telling pic... A very probable cause for fuel supply issues.

If all else fails, you could try cork. Solder may make it heavier & float less, but maybe a judicious layer of epoxy (not much heavier than fuel) might work. In either case, if you work on the float you'd have to re-test/set the fluid height.

[Blurredman]

So last night I fitted my spare (new) float and set it accordingly. And I braved a dark and strictly local 7 mile test ride.
The bike feels good. It definately has quite a nice and linear torque delivery through the RPM.

There are a few points however:
- The fact that the rotation of the ES throttle is much more than a 'modern' bike means more hand movement to pull away. It seemed quite easy to bog.
- However, I realise that the pilot screw I have set to 1.5 turns and not the '2 to 3 turns' as described in the manual. It's likely the idle circuit needs to be richened thus.
- After pulling the clutch in to change gears, the engine speed seems to stay the same for a second or two. Not sure if that is standard for ES (heavier clutch etc?) or due to the leaner idle circuit. The thing is, the main needle is set to the 4th notch (2nd richest), and even then there is a slight chip on the end of it so it might artificially be running richer anyway.

After I got back, I took a picture of the spark plug:

https://scontent-lcy1-1.xx.fbcdn.net/v/t1.15752-9/257927587_4358647310929846_6502139812727257897_n.jpg?_nc_cat=110&ccb=1-5&_nc_sid=ae9488&_nc_ohc=WNZaZy7Bdr4AX_0CVsq&_nc_ht=scontent-lcy1-1.xx&oh=fe8d4a35fea46b4b1a0f835cc5a33768&oe=61BAC9EE



- The clutch was heavy before, but now it's barely possible to to pull on that clutch lever! I never changed the clutch thrust bearing, (it felt really good, actually) but wouldn't have thought that would be an issue when stationary and engine not running. The cable is routed correctly (indeed a new cable), and there is no resistence in the lever itself when cable disconnected.
I suppose it's time to address the two fold issue of both my threaded drain bolt (threaded on the clutch cover, unfortunately), and at the same time just change that bearing. I didn't disasemble the clutch itself (and actually I felt no drag nor slip on my test ride). Or perhaps the clutch thrust mechanism is seizing a little, somehow (?) Interesting.

- I feel slightly twisted when on the bike. This could be because of the broken seat mount, or something else. Bars seem straight. The twist seems to be with my lower body. The bike also seems to gravitate towards the right- as in, I feel an ever so slight effort to keep it further to the left of the lane. This could be because of the twist- or wheel alignment, indeed. (speaking of which I need to lubricate that chain!).

- The brake are not that bad at all actually! I was pleasantly surprised at the effectiveness of the front. It seems just as effective as my long gone Honda CG125, or my Suzuki TS185ER (which I still have, so can compare mentally, legitimately). Maybe the front shoe material is upgraded (?), or maybe i'm just lucky. The rear is fine. Nothing much to speak of there. Of course, the rear has to be actuated even slightly though for that brake light to come on!

- Speaking of which, I notice the brake light only illuminates when the engine is running. No power goes to the bulb when the engine is off. The engine must be running to make that brake light work (and even then it barely works at idle- it seems somewhat dynamo in operation like it is AC - Can anyone 'illuminate' me on that?) All other lights work with the engine off.


- That speedo certainly wanders! It records 10-15 mph sometimes when stationary, and sometimes reads 40, and sometimes 30 when the driven speed has not been changed at all! It does at least seem to be recording the miles reliably. This is with a new cable, by the way! Interesting.

[Puffs]

Good to hear it rides better, & see you progress in tuning the bike!

On the clutch, OK, if it's a new cable, and if the handle is in good condition, it must be inside the engine mechanism. Either the actuation mechanism, or inside the clutch basket.

More hand movement to get the same slide distance (or is it 28mm here? 2mm less!) should make for a lighter throttle handle. Lighter, but less direct. It's no racer.

[Blurredman]

Well tonight I took the clutch cover off and had a good look around- I could see absolutely nothing wrong, other than the fact that the clutch thrust bearing is now groany (it did feel nice initially, which is why I never disasembled the clutch). It is the only bearing I didn't change. Alas with nothing else wrong, the bearing is what I will investigate foremost. The clutch although seemed quiet enough initially, the clutch did 'rattle' when the lever was pulled in the more I drove.

Removal of the clutch was nice and easy, and disasembly of it was too. Inside the clutch I can see the friction plates have nice thickness (will check later but they definitely look barely worn), and the metal friction plates still have that nice friction pattern very evident! So the clutch itself looks fine enough. It wasn't too hard to hammer out the bearing and as you can see it is very dry and very corroded. I have a replacement on order already.




And whilst the clutch cover is off, it's also opportune time to have a look at that threaded drain bolt hole.. The bolt seems like an m8. I have access to an m10 drill and tap, so hopefully it won't be too much of an issue.


Yes, I should replaced this (and cleaned up the clutch itself - yes I will be doing that) before now.


A quick answer to one of my previous questions. Indeed the brake light is DC and should be powered perfectly find with just the ignition on. Or at least, it should be! This is certainly a curious one! So long as it works when the engine is running then that's okay by me..

[Puffs]

Yes that thrust bearing (particularly the cage) looks like it could have been in a flood for a while... That would explain a rumbling/rattling noise, particularly when you pull the clutch, but not necessarily that it is hard to pull the clutch. Or does it?
For the hard pull, I'd expect something that hampers the motion when you pull the lever. Something in that actuation mechanism?

ES 250_2, ES 175_2, Bild 82.gif (10.27 KiB) Viewed 17439 times

On your brake light: maybe one way or another it gets its juice directly from the regulator? Odd.

[Blurredman]

Yes. Agreed. Not sure how the bearing (I mean, it's not in a million pieces or anything) being corroded has anything to do with how tough the clutch was to pull in. Esspecially with an engine off situation, the bearing itself isn't spinning and simply put it wouldn't matter either way whether it was just to push the pressure plate in.. It hasn't collapsed so clearance isn't the issue, and that would be regulated with the clutch cable adjustment. The clutch actuating mechanism is working perfectly smoothly inside the removed clutch cover. It feels nice and the only resistence is the spring on the rod that the cable itself connects to which isn't much. Which would be reduced even more so with a lever...

The only thing I thought interesting was the fact that despite taking off all the nuts of the pressure plate itsef, one of the locknut tab washers which was stuck fast, was keeping the whole clutch assembly intact - until I prised it away and the pressure plate popped up with the force of the 6 springs- this was expected though so precautions were made. That may have been something - it may not have been either. In generation operation on the test ride, other than the clutch lever requiring so much force, the clutch itself felt smooth and worked nicely and smoothly.

[Blurredman]

Okay, so the main component parts (not the discs) of the clutch went into the dish washer for a clean and they've come out 'okay'. Some scrubbing will be required, but the majority of the muck and what have you are gone. I made sure to dry the inner 'cone' of the clutch that mates with the crank, and get that dry asap foremost so that the face wouldn't start rusting/crusting, even the slightest.

I did drill and tap the drain hole in the clutch cover for an M10 size. Unfortunately I did so at a slight angle, so I have filed away at the protruding surface the bolt sits on so that the head will sit flat. The only bolt I have doesn't have thread all the way to the base, so I'll have to use two copper washers- so that will also help flatten out imperfection in my filing angle hopefully. I'll use a tiny bit of RTV on that bolt too I think.


Don't have any pictures of the above, however the new 51106 clutch thrust bearing has arrived, and that can be fitted. I will remember to pre-lube it, as I did with all previous bearings I had installed in the engine, because for some reason the original bearing is dry (shouldn't some of that transmission oil have got to it by 7 miles!?).

[Puffs]

In the dishwasher! Not sure my wife would allow that...

If you cleaned everything & all moving parts look good, maybe that clutch is supposed to be the way it is?

On the dry bearing: I suppose it'll get lube oil supplied via splashing. If oil is too thick, it doesn't splash very well, maybe that's the reason? On a longer run the engine will warm up and the oil will thin. But it raises the questions: oil grade OK? Enough?

Lube everything on assembly. Maybe it was 'hard' because the actuation mechanism was also dry?